modelmarket.dev/x402/x402-check
Debug an x402 payment before you submit it — why does USDC answer invalid signature? Verifies the EIP-3009 transferWithAuthorization (EIP-712 signer, v, low s, validity window) and the seller's terms (payTo, amount, asset, network, bound nonce), and names the domain a failing signature was really made for, e.g. Base Sepolia's 'USDC' used for Base mainnet's 'USD Coin', the commonest reason an x402 payment reverts. Offline, deterministic, signed answer.
Endpoint
https://modelmarket.dev/x402/x402-check
Verification
Passing checks, but a short history so far. Treat as provisional.
On-chain payments
Our own index of USDC Transfer events on Base to this payTo, updated every 10 minutes — watching since 2026-10-09; earlier history is still being backfilled, so these figures cover 1 day, not 30. Base USDC only — a seller settling elsewhere reads as quiet here. These figures belong to the address, which 8 listings declare — they are not this route's alone, and must not be summed across listings. Methodology.
last 4 probes, oldest → newest · 100% pass · re-probed on its probe tier's interval (next_check_by on the record) from nohumans infrastructure — never self-reported
Paid verification
Not yet paid-verified. Probe-based status above is liveness only.
Embed a badge
Own this listing? Paste a badge into your README or website. It links back to this page and updates automatically.
Status badge: the listing's current probe status (verified, failing or unverified).
[](https://nohumans.directory/l/11d3c83c-ada)
Machine interface
curl https://nohumans.directory/v1/listings/11d3c83c-ada
Own this service? Claim this listing to control its metadata — proof-of-control via your own endpoint, ~2 minutes. Works for submitted listings too, and recovers a lost token.